Actually while I do agree that both those things could bring balance issues, I don't agree with fact that it has to be either of those.What you are asking for is either one of two things:
1) Aa overall buff to spears
2) A buff to spears when the player uses them as a primary weapon, but AI is unchanged
Both of these approaches have large problems.
As far as 1) is concerned, spears already play a critical anti-cavalry role from large sweeping battles, to small skirmishes. In addition, they have very long range; are excellent when mounted; and have a large momentum modifier that scales with athletics into late game. Sure, they may not be equal to an 2h axe or 2h sword in terms of raw foot infantry kill count or damage, but nothing comes close to a good spear when used on horseback or against mounted troops.Just like a 1h + shield may never equal a 2h weapon in terms of damage or kills (nor should it) but having a shield gives you far more defense and that versatility can and often will save your life. All weapon types have a niche, and the spear not only fills its niche extremely well, but it also goes above-and-beyond by also being a decent late game foot soldier weapon. No overall buffs are needed.
2) As for changing the weapon to work differently when the player uses it? No other weapon does that, and I don't see why one should get special treatment.
I never thought I'd actually see people who were axe fanboys, or sword fanboys, or spear fanboys, but I was ignorant. They do exist, and they are right here in this thread. It's amazing, and also a little disturbing.
Any buff to the base damage could decrease momentum damage too, so the weapon is just more effectice at lower speeds, but not more efficient against, or on a charging horse.
Moreover, changes like increasing attack speed don't actually make spears any more efficient to counter cavalry, it could even make timing harder if you don't spear brace.
In term of raw damage they are not even close to one handed weapons, in "late game" with a polearm skill in the 400's, you still hit a lot slower, and deal a lot less damage than you would with a single overhead one-handed attack.
Spears being bad at close range is not necessarily a bad thing, but at longer ranges (wich are impossible to maintain unless you have a lot more athletics than your ennemy), it's still very easy to block and not even really punishing when it hits.
And currently there is nothing stopping you from bringing an other weapon along with your spear, you just loose one slot.
That would be the biggest difference, not being forced to bring a secondary weapon along with your spears to deal effectively with everything but cavalry.
And on AI, you're not quite right, the AI with spears is actually really bad against cavalry in the vanilla game, swordsmen are much better (there are tons of tests for that), spear brace is really effective however, but not all spears can brace (T5 sturgians spearmen can't).
And on top of it, they are always packing a sword along with the spear, and will automatically swap for it in melee combat.
We don't have to be spear fanboys to regret that, if you just try to go full spear on foot (not swingable) you will instantly notice that it's not as effective as basically everything else.
The game gave us an option, we tried it and are disappointed because it doesn't work that well, and that's not only not realistic, but it also doesn't bring anything to the game.
The AI actually fighting with spears would be fun to deal with, and probably more interesting to play than if they are just anti-cavalery infantry, and fight like everything else against foot troops.
And for the players, it brings an other way to play, nothing wrong with that to me.
Just noticed five bucks basically said the same things than I just did, but better.
You got the idea, spears are almost only anti-cav weapons currently, that works only for braceable spears on AI, and the player basically have to use spears with 4 attacks directions if he actually wants to be effective (so two handed weapon style polearms and not spears).